Pretreatment of piggery wastewater by a stable constructed microbial consortium for improving the methane production

A stable aerobic microbial consortium, established by successive subcultivation, was employed to solubilize the solid organic fraction in swine wastewater. In the 30 days' successive biological pretreatments, 30–38% of volatile solids and 19–28% total solids in raw slurry were solubilized after 10 hours at 37 °C. Meanwhile, soluble chemical oxygen demand (COD) and volatile fatty acid increased by 48%–56% and 600%–750%, respectively. Furthermore, the molecular microbial profile of the consortium in successive pretreatment was conducted by denaturing gradient gel electrophoresis (DGGE). The results indicated that bacterial species of the consortium rapidly overgrew the indigenous microbial community of raw water, and showed a stable predominance at the long-term treatment. As a consequence of biological pretreatment, pretreatment shortened digestion time by 50% and increased biogas production by 45% compared to raw water in the anaerobic process. The microbial consortium constructed herein is a potential candidate consortium for biological pretreatment of swine wastewater to enhance biogas production.